Coke oven batteries defined by a set of ovens, typically 25-100 ovens, built side by side, delimited by opposing sidewalls made of refractory bricks and being built as hollow sections to define, internally, the renowned heating or combustion chambers are well known in the art.
The opposing sidewalls are seated on a generally concrete base and are closed on the upper part by a top wall which is also made of refractory material, each oven being closed by a ceiling (roof), also made of refractory material and provided with loading ports to enable the loading of coal, which after a 16-36 hour cycle, is transformed into coke due to the heating process which they are subjected to within each oven (FIGS. 1, 2 and 3).
Each hollow sidewall has its heating chambers arranged in vertical columns sequentially laid along the length of each internal wall and provided underneath with at least one ceramic burner, which depending on the number of combustion flues, are arranged along the length of said opposite sidewalls, generally every 500 mm, and it should be noted that the dimensions of each oven of the battery may range from about 400 mm to 700 mm in width and from about 3500 mm to 7500 mm in height and moreover a length of about 13000 mm, and with each two adjacent ovens sharing a common sidewall.
The opposite sidewalls of each oven are those that define the left and right sides of the respective oven, over the entire height of the latter. These sidewalls are made of refractory bricks, usually made of silica, forming the so called “rows”. The roof of the ovens and the top of the combustion flues in each sidewall are always built with bricks arranged in “rows” and made of silica, fireclay, clinker or insulating material (FIGS. 1, 2 and 3).
It turns out that the coke ovens described above have progressive wear of their opposing sidewalls, and this wear is more pronounced on the anterior and posterior end regions of said walls. Thus, in many cases there is no need to entirely replace one or more of these coke ovens sidewalls. It is enough to simply replace the opposite end portions of said walls.
Often, the damaged end portions, which actually require repair by being replaced by new portions, represent altogether only about 30% to 40% of the total extent of a sidewall. Thus, replacing only the damaged or worn end portions of the sidewalls represents considerable savings in the repair operations of coke oven batteries.
While only partial replacement of the worn sidewalls is desirable, techniques that have been applied for the partial replacement of the sidewalls require laborious and expensive procedures to obtain an adequate joint between the ‘new refractory bricks’ and ‘old refractory bricks’, keeping the reformed walls with characteristics such as the resistance to the expansion of coal, the absence of gas leakage, elasticity between the new end portion and the old middle portion of each renovated wall.
In conventional techniques, the removal of the worn end portions of each wall is obtained by performing a flat vertical cutting operation in each of the regions bordering the middle portion of the wall to be maintained. The provision of these two cuts in the bordering regions defines the two flat and opposite end faces, arranged in orthogonal planes to their wall plane and against these walls there must be settled and fixed, watertight and with the necessary mechanical locking, the confronting flat faces of the adjacent bricks in the first row of the new refractory bricks that will form the two end portions to be mounted and solidly built in the middle portion of the old wall.
Due to the formation of flat joints between the new end portions and the middle portion of the old wall, the fixing of the flat faces of the old bricks on the flat faces of the new refractory bricks requires not only the necessary seal to resist the operating conditions of the oven, but also the mechanical forces of outwardly expansion of said sidewalls, during operation of the oven, by virtue of the expansion of the coal charge being converted into coke.
In this method for the partial repair of the coke oven walls, the strength of the junction regions, against forces transversal to the wall plane, requires the provision of ceramic welding between the old bricks and the new bricks by means of costly and laborious ceramic welds over the entire height of the junction region, which generally corresponds to the entire height of the sidewall of the oven.
In a battery composed of one hundred ovens, each of which may have up to about 7000 mm in height, each hollow wall may have four junction regions, two at each end, to be completed with the use of respective ceramic welds, which makes this operation extremely time-consuming and expensive due to the characteristics of such a ceramic welding process.
Besides the above-identified deficiencies derived from the requirement for the provision of a ceramic weld in the flat junction between the new and old bricks, this well-known method also requires maintenance and even the periodic replacement of these ceramic weld joints every two or three years, involving huge expenses for the maintenance of these ovens in suitable operating conditions.
Another drawback of the known methods is to restrict the number of adjacent walls to be partially or completely repaired, depending on the maximum allowable span for the maintenance of the travel rails of the loading machine which moves above the furnace battery. Typically, the number of adjacent walls to be reformed simultaneously cannot exceed five, thus limiting the number of walls to be simultaneously repaired or replaced.